On Mon, Oct 25, 1999 at 09:26:47AM -0700, Jason Thorpe wrote:
> On Mon, 25 Oct 1999 18:34:45 +0900 (JST)
> nisimura@itc.aist-nara.ac.jp (Toru Nishimura) wrote:
>
> > Now, is it possible to mmap the whole framebuffer segment in a single
> > TLB? Alpha processor allows to have 'fat TLBs' as MIPS R4000. It
> > would bring big saving for Xserver, won't it?
>
> Yes, there's a "granularity hint" bit in the PTE that the PALcode can use
> to install Fat TLB Entries.
>
> However, there's not really a good interface between the VM system and
> the pmap and device driver to take advantage of it. It's all still done
> one page at a time.
There are a few ports that could take advantage of such an interface --
this kind of "giant page" hack is becoming increasingly popular. All
the x86 processors in recent memory have had it (including the clones,
at least the ones that have survived) and other Unices that run on the
x86 seem to use it.
--
Thor Lancelot Simon tls@rek.tjls.com
"And where do all these highways go, now that we are free?"